We are studying the function of extracellular matrix components and their molecular interactions with cell surfaces. The Cell-substratum attachment glycoprotein laminin is being studied at the molecular level with synthetic peptides and with their corresponding antibodies to define the active domains for cell attachment, growth, migration, and type IV collagen binding. Our data have identified an active site for cell attachment and for cell migration. This region has homology to epidermal growth factor and likely is important in indicating cell-matrix interactions in development and in regeneration. Cell-matrix interactions are regulated by cell surface matrix receptors. Using molecular and biochemical approaches, we are identifying and characterizing these components on fibroblastic and on neuronal cells. Our data define how cells interact with cell attachment proteins and with collagens. These and other studies indicate that specific cell surface receptors bind to matrix components and thus control the biological responses of the cells to the matrix.